The present invention relates to a fabric foundation for an ink ribbon which is used for printing while being impregnated with a liquid ink.
Ink ribbons impregnated with a liquid ink have been used in various impact printers such as wire dot printers and daisy wheel printers.
The recent trend in such printers is toward higher printing speed. With these printers, printing is conducted while running an ink ribbon and, hence, a monentary rubbing between the ink ribbon and a printing paper, which is caused when striking with a print head, becomes violent with an increased printing speed.
Further, the number of constituent sheets of duplicate chits or slips, and the like has been increased and increasingly, printing is conducted on such thick paper sheets as used in deposit passbooks, and the like.
These cases require that a stronger striking power be exerted on the ink ribbon.
Owing to such increased rubbing and striking forces, ink ribbons are used under extremely severe conditions, resulting in damage to the ink ribbons in a short period of time.
This tendency is of particular concern with seamless ink ribbons because it is difficult to produce these ribbons having a large entire length.
The seamless ink ribbon is fabricated by weaving a tubular fabric as shown in FIG. 3(A) according to an endless plain weaving method and cutting crosswise the tubular fabric to a desired width, yielding ring-like fabric foundations with no seam for the seamless ink ribbon as shown in FIG. 3(B). In FIG. 3(A), the vertical direction of the tube corresponds to the warp yarn direction, and the circumferential direction of the tube corresponds to the weft yarn direction. FIG. 3(C) is an enlarged partial plan view showing the thus obtained seamless ink ribbon fabric foundation, wherein numeral 1 denotes a warp yarn and numeral 2 denotes a weft yarn.
In view of the foregoing, it is an object of the present invention to provide a fabric foundation for an ink ribbon, particularly for a seamless ink ribbon, which is hardly damaged under severe printing conditions such as high speed and strong striking force, offering an extended life.
This and other objects of the present invention will become apparent from the description hereinafter.